(339d) Effects of Crystal Structure On Nickel Catalysts: A Experimental Approach

The development of the hydrogen economy requires a safe, efficient, and environmentally friendly method for the production of hydrogen. Urea electrolysis has been shown to produce pure hydrogen at low temperature, pressure, and energy consumption in alkaline media.¹ Nickel has been shown to be the most active catalyst for the electrochemical oxidation of urea. However, crystal structure and orientation drastically affects the performance in heterogenous catalysis. The catalyst crystal structure can be modified using a variety of techniques including alloying with other metals² or annealing.³ It is plausible that the change in surface structure should have on effect on its catalytic properties.

In this study nickel catalysts including polycrystalline nickel [predominantly Ni (1 1 1)] and Ni (1 0 0) were investigated. The activity of both the polycrystalline nickel and Ni (1 0 0) were monitored using cyclic voltammetry and potential step voltammetry. In the presence of 0.33 M urea it has been shown that the Ni (1 0 0) is the most active catalyst with an oxidation current of 1.02±0.01´10^-1 A cm^-2 compared to 0.41±0.01´10^-1 for the polycrystalline Ni catalyst. The changes in the activity and onset potential indicate that the crystal structure affects the performance of the electrode. Density functional theory (DFT) confirmed differences in urea adsorption between Ni (1 1 1) and Ni (1 0 0), confirming that changes in the crystal structure will affect the performance of the electrode.